U.S. Geothermal Power at Present

Part 5 of Geothermal Energy Under Our Feet. Today’s U.S. geothermal industry is a $2-billion per-year enterprise involving over 2800 MW of electricity generation capacity, about 620 MW of thermal energy capacity in direct-use applications such as indoor heating, greenhouses, food drying, and aquaculture, and over 7,300 MW of thermal energy capacity from geothermal heat […]

Geothermal Resource Descriptions

Part 4 of Geothermal Energy Under Our Feet. Hydrothermal A hydrothermal system is defined as a subterranean geothermal reservoir that transfers heat energy upward by vertical circulation of fluids driven by differences in fluid density that correspond to differences in temperature (see Figure 2). Hydrothermal systems can be classified into two types—vapor-dominated and hot water— […]

Geothermal Resource Definitions

Part 3 of Geothermal Energy Under Our Feet. The total resource base in the United States, both renewable and non-renewable, is very large, with an energy content of over 657,000 billion barrels of oil equivalent (BBOE), or nearly 50,000 times the annual current rate of national energy consumption. Figure 1 shows graphically what the total […]

United States Geothermal Resources

Part 2 of Geothermal Energy Under Our Feet. The United States possesses vast underground stores of heat whose full potential has yet to be realized. The Earth’s interior reaches temperatures greater than 4,000°C (>7,200°F), and this geothermal energy flows continuously to the surface. The energy content of domestic geothermal resources to a depth of 3 […]

Under Our Feet: Geothermal Energy

Part 1 of Geothermal Energy Under Our Feet. The Earth houses a vast energy supply in the form of geothermal resources. Domestic resources are equivalent to a 30,000-year energy supply at our current rate for the United States! In fact, geothermal energy is used in all 50 U.S. states today. But geothermal energy has not […]

Geothermal Power Plants: from light to water

Part 3 of Geothermal Energy: Power from the Depths of the Earth. Flip a switch and light up a room—what could be easier? Push a button on the TV remote control and be entertained. It all seems so simple that we are often unaware of the true environmental and social cost of these conveniences—and who […]

Geothermal Power: A Clear Advantage

Part 2 of Geothermal Energy: Power from the Depths of the Earth. Geothermal energy delivers some powerful environmental and economic benefits. If you live in an area that uses geothermal resources for electricity production, you’re quite fortunate. Consider Lake County, California, which is home to many of the geothermal power plants at our nation’s best-developed […]

Geothermal Energy: Power from the Depths of the Earth

Part 1 of Geothermal Energy: Power from the Depths of the Earth. The Earth’s crust is a bountiful source of energy—and fossil fuels are only part of the story. Heat or thermal energy is by far the more abundant resource. To put it in perspective, the thermal energy in the uppermost six miles of the […]

Geothermal Heat Pumps Make Sense for Homeowners

Geothermal heat pumps are one of the most efficient ways to heat and cool a home and provide hot water. More and more homeowners are discovering the benefits of these systems, which tap the relatively constant temperature of the Earth a few feet underground, for both new homes and retrofits in existing houses. Geothermal heat […]

Geothermal Heat Pumps & Other Energy Sources

Part 13 of Buying and Using Renewable Energy at Home. One of the most energy-efficient options for heating and cooling your home draws on another form of renewable energy—geothermal energy, or heat from the earth. This is not the hot steam and heat that comes from deep underground (discussed here). Rather, geothermal heat pumps draw […]

Clean Energy Choices for Today

Part 4 of Buying and Using Renewable Energy at Home. The following briefly describes renewable energy technologies that might be offered in green pricing programs or competitive markets in your area. If you do not currently have the option to choose your electricity supplier, contact your utility to find out what their plans are regarding […]

Overview: Geothermal Heat Pumps

Part 1 of Geothermal Heat Pumps. If you’re planning to build a new house, office building, or school, or replace your heating and cooling system, you may want to consider a geothermal heat pump (GHP) system. GHP systems are also known as GeoExchange, ground-source, or water-source heat pumps (as opposed to air-source heat pumps). Regardless […]

Air-Source Heat Pumps

Part 1 of Air-Source Heat Pumps. There are two common types of heat pumps: air-source heat pumps and geothermal heat pumps (GHPs). Either one can keep your home warm in the winter and cool in the summer. An air-source heat pump pulls its heat indoors from the outdoor air in the winter and from the […]